What is Go-oo?

 ??What is Go-oo

Go-oo is a community-developed fork of Sun's Open Office office suit. Go-oo contains features and improvements that for technical or legal reasons cannot be included in Sun's version of Open Office. Most Linux distributions today use Go-oo instead of the standard Open Office packages, however, the splash screen and "About" dialogs usually remain the standard Open Office versions. This is at Sun's request, to enhance brand recognition and is in stark contrast to Mozilla's stance on Firefox forks, notably Iceweasel.

Although Open Office is open source, Sun does not accept contributions from outside Sun unless the developer gives Sun ownership of the contributed code. This ownership means that Sun can release this code under what ever license Sun chooses. Most code is released twice: once in OOo (Open Office) under the GPL license, and once again in Star Office under a proprietary Sun license. Star Office, Sun's commercial office suit, is built from much of the same code base as OOo, however being a proprietary application it cannot incorporate GPL code.

Go-oo logo

Community frustration regarding Sun's licensing requirements and refusal to add critical features catalyzed several forks of Open Office, which is explicitly permitted under the GPL license. Go-oo is the leading OOo fork for Linux, incorporating enhanced compatibility with competing office suits, snappier performance, and additional features. Compatibility with other office suites is provided by filters capable of parsing Microsoft Office's native OOXML format, MS Works, and Lotus Word Pro files. Snappier performance is seen is faster startup times and improved code profiling. Some of the more useful features in Go-oo that are missing from OOo include SVG support, VBA macro support, 3D transition effects, and a built-in multimedia framework.

What is an IP Address?

Internet Protocol Address (or IP Address) is an unique address that computing devices such as personal computers, tablets, and smartphones use to identify itself and communicate with other devices in the IP network. Any device connected to the IP network must have an unique IP address within the network. An IP address is analogous to a street address or telephone number in that it is used to uniquely identify an entity.

Dotted Decimals

The traditional IP Addresses (known as IPv4) uses a 32-bit number to represent an IP address, and it defines both network and host address. A 32-bit number is capable of providing roughly 4 billion unique numbers, and hence IPv4 addresses running out as more devices are connected to the IP network. A new version of the IP protocol (IPv6) has been invented to offer virtually limitless number of unique addresses. An IP address is written in "dotted decimal" notation, which is 4 sets of numbers separated by period each set representing 8-bit number ranging from (0-255). An example of IPv4 address is 216.3.128.12, which is the IP address previously assigned to iplocation.net.

An IPv4 address is divided into two parts: network and host address. The network address determines how many of the 32 bits are used for the network address, and remaining bits for the host address. The host address can further divided into subnetwork and host number.

Class A, B, C and CIDR networks

Traditionally IP network is classified as A, B or C network. The computers identified the class by the first 3 bits (A=000, B=100, C=110), while humans identify the class by first octet(8-bit) number. With scarcity of IP addresses, the class-based system has been replaced by Classless Inter-Domain Routing (CIDR) to more efficiently allocate IP addresses.

Class	Network Address	Number of Hosts	Netmask
CIDR	/4	240,435,456	240.0.0.0
CIDR	/5	134,217,728	248.0.0.0
CIDR	/6	67,108,864	252.0.0.0
CIDR	/7	33,554,432	254.0.0.0
A	/8 (1-126)	16,777,216	255.0.0.0
CIDR	/9	8,388,608	255.128.0.0
CIDR	/10	4,194,304	255.192.0.0
CIDR	/11	2,097,152	255.224.0.0
CIDR	/12	1,048,576	255.240.0.0
CIDR	/13	524,288	255.248.0.0
CIDR	/14	262,144	255.252.0.0
CIDR	/15	131,072	255.254.0.0
B	/16 (128-191)	65,534	255.255.0.0
CIDR	/17	32,768	255.255.128.0
CIDR	/18	16,384	255.255.192.0
CIDR	/19	8,192	255.255.224.0
CIDR	/20	4,096	255.255.240.0
CIDR	/21	2,048	255.255.248.0
CIDR	/22	1,024	255.255.252.0
CIDR	/23	512	255.255.254.0
C	/24 (192-223)	256	255.255.255.0
CIDR	/25	128	255.255.255.128
CIDR	/26	64	255.255.255.192
CIDR	/27	32	255.255.255.224
CIDR	/28	16	255.255.255.240
CIDR	/29	8	255.255.255.248
CIDR	/30	4	255.255.255.252

Note: (1) 127 Network Address reserved for loopback test. (2) Class D (224-247, Multicast) and Class E (248-255, Experimental) are not intended to be used in public operation. 

Public and Private IP Addresses 

In order to maintain uniqueness within global namespace, the IP addresses are publicly registered with the Network Information Center (NIC) to avoid address conflicts. Devices that need to be publicly identified such as web or mail servers must have a globally unique IP address, and they are assigned a public IP address. Devices that do not require public access may be assigned a private IP address, and make it uniquely identifiable within one organization. For example, a network printer may be assigned a private IP address to prevent the world from printing from it. To allow organizations to freely assign private IP addresses, the NIC has reserved certain address blocks for private use. A private network is a network that uses RFC 1918 IP address space. The following IP blocks are reserved for private IP addresses.

Class	Starting IP Address	Ending IP Address
A	10.0.0.0	10.255.255.255
B	172.16.0.0	172.31.255.255
C	192.168.0.0	192.168.255.255

In addition to above classful private addresses, 169.254.0.0 through 169.254.255.255 addresses are reserved for Zeroconf (or APIPA, Automatic Private IP Addressing) to automatically create the usable IP network without configuration.

What is loopback IP address? 

The loopback IP address is the address used to access itself. The IPv4 designated 127.0.0.1 as the loopback address with the 255.0.0.0 subnet mask. A loopback interface is also known as a virtual IP, which does not associate with hardware interface. On Linux systems, the loopback interface is commonly called lo or lo0. The corresponding hostname for this interface is called localhost.

The loopback address is used to test network software without physically installing a Network InterfaceCard (NIC), and without having to physically connect the machine to a TCP/IP network. A good example of this is to access the web server running on itself by using http://127.0.0.1 or http://localhost.

What is a Hybrid Vehicle?

 ??What is a Hybrid Vehicle

A hybrid car is an automobile that has two or more major sources of propulsion power. Most hybrid cars currently marketed to consumers have both conventional gasoline and electric motors, with the ability to power the vehicle by either one independently or in tandem. These vehicles are appropriately termed gas-electric hybrids. Other power sources may include hydrogen, propane, CNG, and solar energy. The technology used depends on the goals set for the vehicle, whether they be fuel efficiency, power, driving range, or reduced greenhouse gas emissions. Consumer oriented hybrid cars, which have been on the market for about ten years, are usually tuned for reduced emissions and driving range. Additionally, owners of hybird vehicles often enjoy social benefits such as prestige and discounted secondary services. Some Chicago hotels as well as hotels in other cities give parking discounts to people driving hybrid cars. Corporate and government fleets that have been in service for twenty years or more are usually tuned for fuel efficiency, often at the cost of driving range, power, and hydrocarbon emissions.

A gasoline-electric hybrid car has one or two auxiliary electric motors that supplement the main gasoline engine. Compared to conventional automobiles, the gasoline engine in a gas-electric hybrid is smaller, less powerful, and more efficient. Although the gasoline engine alone would be sufficient to power the vehicle under most circumstances, during maneuvers requiring unusually high power the electric motor is used as well. These conditions include passing, hill climbing, and acceleration from a standstill. Some hybrid cars, such as the Toyota Prius, shut down the gasoline engine under conditions in which the electric motor alone would suffice, such as coasting and breaking. In fact, the Toyota Prius has a special electric-only mode designed for stop-and-go traffic. This is made possible by the super heavy duty electric motor used in the Prius, which is capable of propelling the vehicle from a standstill without the gasoline assist. Thus, in contrast to most other hybrid vehicles, the Prius actually uses the electric motor more than the gasoline engine.

a Hybrid Vehicle logo

Many of the technologies found in hybrid vehicles would benefit vehicles of any type, including conventional gasoline automobiles. However, the engineering and manufacturing costs associated with these technologies often would increase the price of the vehicle to the point where the fuel savings are negligible in comparison. Only in tax-subsidized electric and hybrid vehicles are these technologies practical, in which associated cost increases are absorbed by the government instead of the manufacturer or consumer. These technologies include regenerative braking, aerodynamic refinements, and lightweight building materials.

What is a Subnet Mask?

An IP address has two components, the network address and the host address. A subnet mask separates the IP address into the network and host addresses (<network><host>). Subnetting further divides the host part of an IP address into a subnet and host address (<network><subnet><host>) if additional subnetwork is needed. Use the Subnet Calculator to retrieve subnetwork information from IP address and Subnet Mask. It is called a subnet mask because it is used to identify network address of an IP address by perfoming a bitwise AND operation on the netmask.

A Subnet mask is a 32-bit number that masks an IP address, and divides the IP address into network address and host address. Subnet Mask is made by setting network bits to all "1"s and setting host bits to all "0"s. Within a given network, two host addresses are reserved for special purpose, and cannot be assigned to hosts. The "0" address is assigned a network address and "255" is assigned to a broadcast address, and they cannot be assigned to hosts.

Examples of commonly used netmasks for classed networks are 8-bits (Class A), 16-bits (Class B) and 24-bits (Class C), and classless networks are as follows:

Class	Address	# of Hosts	Netmask (Binary)	Netmask (Decimal)
CIDR	/4	240,435,456	11110000 00000000 00000000 00000000	240.0.0.0
CIDR	/5	134,217,728	11111000 00000000 00000000 00000000	248.0.0.0
CIDR	/6	67,108,864	11111100 00000000 00000000 00000000	252.0.0.0
CIDR	/7	33,554,432	11111110 00000000 00000000 00000000	254.0.0.0
A	/8	16,777,216	11111111 00000000 00000000 00000000	255.0.0.0
CIDR	/9	8,388,608	11111111 10000000 00000000 00000000	255.128.0.0
CIDR	/10	4,194,304	11111111 11000000 00000000 00000000	255.192.0.0
CIDR	/11	2,097,152	11111111 11100000 00000000 00000000	255.224.0.0
CIDR	/12	1,048,576	11111111 11110000 00000000 00000000	255.240.0.0
CIDR	/13	524,288	11111111 11111000 00000000 00000000	255.248.0.0
CIDR	/14	262,144	11111111 11111100 00000000 00000000	255.252.0.0
CIDR	/15	131,072	11111111 11111110 00000000 00000000	255.254.0.0
B	/16	65,534	11111111 11111111 00000000 00000000	255.255.0.0
CIDR	/17	32,768	11111111 11111111 10000000 00000000	255.255.128.0
CIDR	/18	16,384	11111111 11111111 11000000 00000000	255.255.192.0
CIDR	/19	8,192	11111111 11111111 11100000 00000000	255.255.224.0
CIDR	/20	4,096	11111111 11111111 11110000 00000000	255.255.240.0
CIDR	/21	2,048	11111111 11111111 11111000 00000000	255.255.248.0
CIDR	/22	1,024	11111111 11111111 11111100 00000000	255.255.252.0
CIDR	/23	512	11111111 11111111 11111110 00000000	255.255.254.0
C	/24	256	11111111 11111111 11111111 00000000	255.255.255.0
CIDR	/25	128	11111111 11111111 11111111 10000000	255.255.255.128
CIDR	/26	64	11111111 11111111 11111111 11000000	255.255.255.192
CIDR	/27	32	11111111 11111111 11111111 11100000	255.255.255.224
CIDR	/28	16	11111111 11111111 11111111 11110000	255.255.255.240
CIDR	/29	8	11111111 11111111 11111111 11111000	255.255.255.248
CIDR	/30	4	11111111 11111111 11111111 11111100	255.255.255.252

Subnetting an IP network is to separate a big network into smaller multiple networks for reorganization and security purposes. All nodes (hosts) in a subnetwork see all packets transmitted by any node in a network. Performance of a network is adversely affected under heavy traffic load due to collisions and retransmissions.

Applying a subnet mask to an IP address separates network address from host address. The network bits are represented by the 1's in the mask, and the host bits are represented by 0's. Performing a bitwise logical AND operation on the IP address with the subnet mask produces the network address. For example, applying the Class C subnet mask to our IP address 216.3.128.12 produces the following network address:

IP:   1101 1000 . 0000 0011 . 1000 0000 . 0000 1100  (216.003.128.012)
Mask: 1111 1111 . 1111 1111 . 1111 1111 . 0000 0000  (255.255.255.000)

      1101 1000 . 0000 0011 . 1000 0000 . 0000 0000  (216.003.128.000)

      ---------------------------------------------

Subnetting Network 

Here is another scenario where subnetting is needed. Pretend that a web host with a Class C network needs to divide the network so that parts of the network can be leased to its customers. Let's assume that a host has a network address of 216.3.128.0 (as shown in the example above). Let's say that we're going to divide the network into 2 and dedicate the first half to itself, and the other half to its customers.

   216 .   3 . 128 . (0000 0000)  (1st half assigned to the web host)

   216 .   3 . 128 . (1000 0000)  (2nd half assigned to the customers)

The web host will have the subnet mask of 216.3.128.128 (/25). Now, we'll further divide the 2nd half into eight block of 16 IP addresses.

   216 .   3 . 128 . (1000 0000)  Customer 1 -- Gets 16 IPs (14 usable)
   216 .   3 . 128 . (1001 0000)  Customer 2 -- Gets 16 IPs (14 usable)

   216 .   3 . 128 . (1011 0000)  Customer 4 -- Gets 16 IPs (14 usable)
216 .   3 . 128 . (1010 0000)  Customer 3 -- Gets 16 IPs (14 usable)
   216 .   3 . 128 . (1100 0000)  Customer 5 -- Gets 16 IPs (14 usable)

   216 .   3 . 128 . (1111 0000)  Customer 8 -- Gets 16 IPs (14 usable)
216 .   3 . 128 . (1101 0000)  Customer 6 -- Gets 16 IPs (14 usable)
   216 .   3 . 128 . (1110 0000)  Customer 7 -- Gets 16 IPs (14 usable)
   -----------------------------

   255 . 255 . 255 . (1111 0000)  (Subnet mask of 255.255.255.240)

You may use Subnet Calculator to ease your calculation.

CIDR - Classless Inter Domain Routing 

Classless InterDomain Routing (CIDR) was invented to keep the Internet from running out of IP Addresses. The IPv4, a 32-bit, addresses have a limit of 4,294,967,296 (2³²) unique IP addresses. The classful address scheme (Class A, B and C) of allocating IP addresses in 8-bit increments can be very wasteful. With classful addressing scheme, a minimum number of IP addresses allocated to an organization is 256 (Class C). Giving 256 IP addresses to an organization only requiring 15 IP addresses is wasteful. Also, an organization requiring more than 256 IP addresses (let's say 1,000 IP addresses) is assigned a Class B, which allocates 65,536 IP addresses. Similarly, an organization requiring more than 65,636 (65,634 usable IPs) is assigned a Class A network, which allocates 16,777,216 (16.7 Million) IP addresses. This type of address allocation is very wasteful.

With CIDR, a network of IP addresses is allocated in 1-bit increments as opposed to 8-bits in classful network. The use of a CIDR notated address can easily represent classful addresses (Class A = /8, Class B = /16, and Class C = /24). The number next to the slash (i.e. /8) represents the number of bits assigned to the network address. The example shown above can be illustrated with CIDR as follows:

   216.3.128.12, with subnet mask of 255.255.255.128 is written as
   216.3.128.12/25


   Similarly, the 8 customers with the block of 16 IP addresses can be
written as:


   216.3.128.129/28, 216.3.128.130/28, and etc.

With an introduction of CIDR addressing scheme, IP addresses are more efficiently allocated to ISPs and customers; and hence there is less risk of IP addresses running out anytime soon. For detailed specification on CIDR, please review RFC 1519. With introduction of additional gaming, medical, applicance and telecom devices requiring static IP addresses in addition to more than 6.5 billion (July 2006 est.) world population, the IPv4 addresses with CIDR addressing scheme will eventually run out. To solve shortage of IPv4 addresses, the IPv6 (128-bit) address scheme was introduced in 1993.

What is IPv6 Address?

Internet Protocol Version 6 (or IPv6) is a successor of IPv4 Address standard developed by IETF, which is designed to solve IPv4 address exhaustion problem. IPv4 uses a 32-bit numbering scheme to represent an IP address, which has an address space of 232 or 4.3 billion. IPv6, on the other hand, uses 128-bit numbering scheme (2128) which has big enough address space for many decades to come. IPv6 is intended to replace the IPv4, but the introduction of CIDR (Classless Inter-Domain Routing) allocation scheme in 1993 within the IPv4 prolonged lifespan of IPv4 Addresses. With an anticipation of smartphones, tablets, smart appliances and other electronic devices joining Internet every day, IPv4 address space will eventually exhaust. As of May 2014 per Google Statistics, 96% of Internet traffic is IPv4 and only 4% is represented by IPv6. IPv4 and IPv6 are not interoperable by design, so the transition from IPv4 to IPv6 require "transition mechanism" such as Stateless IP/ICMP Translation, Transport Relay, 6rd and other IPv6 transition mechanisms to make them interoperable.

IPv6 Address Types

IPv6 addresses are classified into three categories: unicast, anycast and multicast addressing.

Unicast Address - An unicast IP address is an identifier for a single network interface. An IPv6 packet sent to an unicast address is delivered to a single interface.

Anycast Address - An anycast IP address is identifier for a set of interfaces assigned to a group but belonging to different nodes. An IPv6 packet sent to an anycast address is delivered to a single node closest to the sender identified by the routing algorithm.

Multicast Address - A multicast IP address is identifier for a set of interfaces that may belong to differentn nodes. An IPv6 packet sent to a multicast address is delivered to all interfaces identified by the multicast address.

Unlike IPv4 addressing scheme, the IPv6 addressing scheme does not implement broadcast address. Instead, IPv6 implements multicast address to send packets to a group of nodes and avoids distributing to every nodes in the network. IPv6 also has a scope, which specifies which part of the network it's address is valid and unique.

Coloned Decimals

The IPv6 addresses are comprised of 128-bits (or 8 groups of 4 hexadecimal digits separated by colons), with possibility of omitting zeros to abbreviate the full address. An example of IPv6 address may look like 2001:0db8:0012:0001:3c5e:7354:0000:5db1. For convenience, an IPv6 address can be represented in shorter notation by omitting leading zeros. The example address above can be also be represented as 2001:db8:12:1:3c5e:7354:0:5db1.

When abbreviating IPv6 address, the following rules apply:

One or more leading zeros in any group of 8 hexadecimal digits can be removed. For example, 0012 can be written 12 and 0000 can be converted to 0. (see example above).

Consecutive group of zeros are replaced with a double colon ::. The loopback address, 0000:0000:0000:0000:0000:0000:0000:0001 can be abbreviated to ::1.

What are the differences between IPv4 and IPv6?

The IPv4 and IPv6 share a similar architecture, and they will coexist until IPv6 completely replaces the IPv4.

IPv4 is represented by 32-bit number, and IPv6 is represented by 128-bit number. This translates to 4.3 billion address space for IPv4 and 340 trillion address space for IPv6.

IPv4 is separated by 4 groups of 2 hexadecimal digits by a dot, whereas IPV6 is separated by 8 groups of 4 hexadecimal digits by a colon.

IPv4 does not support short-hand notation, but IPv6 does by omitting leading zeros.

Why is IPv6 matter?

With an explosive demand for smartphones, tablets and computers, more IP addresses are needed than IPv4 can support. There are over 7 billion people in the world with phones, tablets and computers each requiring an IP address. The IPv4 has an address space of 4.3 billion, which will soon exhaust. The transition from IPv4 to IPv6 is necessary, and they will coexist as they are not interoperable.

The users will not likely notice the difference or even notice it. With over 95% of IP addresses being IPv4, it will be quiet some time before we'll see all devices communicating via IPv6.

 ?? What is a MAC Address 

MAC, Media Access Control, address is a globally unique identifier assigned to network devices, and therefore it is often referred to as hardware or physical address. MAC addresses are 6-byte (48-bits) in length, and are written in MM:MM:MM:SS:SS:SS format. The first 3-bytes are ID number of the manufacturer, which is assigned by an Internet standards body. The second 3-bytes are serial number assigned by the manufacturer.

MAC layer represents layer 2 of the TCP/IP (adopted from OSI Reference Model), where IP represents layer 3. MAC address can be thought of as supporting hardware implementation whereas IP address supports software implementation. MAC addresses are permanently burned into hardware by hardware manufacturer, but IP addresses are assigned to the network devices by a network administrator. DHCP relies on MAC address to assign IP addresses to network devices.

How do I find a MAC address of network device?

Operating Systems support various command-line and GUI utilities to allow users to find MAC address of the system. On Unix variants including Solaris and Linux support "ifconfig -a", "ip link list" or "ip address show" command that displays MAC address of the network device among other useful information. Windows including NT, 2000, XP and 2003 support "ipconfig /all" command that displays MAC address. On a MacOS, one can find MAC address by opening "System Preferences", then selecting "Network".

What is a Web Browser?

 ?? What is a Web Browser 

A web browser is a program that lets a human access webpages on the World Wide Web. At a bare minimum, a web browser must be able to make HTTP requests and to present parsed HTML to the user in a form that he can understand. Most modern browsers present the user with a flat document that contains text and pictures, according to the HTML page received. Others may present serial text only, or even read the page aloud. While most people interact with their browser with a mouse, many advanced web browsers such as Opera provide full keyboard and voice control. Also, there are specialty browsers designed for people with physical handicaps and other disabilities. For use in a low-resources environment, text-only web browsers such as Lynx may be used.

In addition to the text and pictures of standards-compliant HTML code, most of today's web browsers can display video, play music, and provide a limited amount of scripting ability. While these abilities do afford the webmaster the ability to design more elaborate websites, not all web browsers interpret the non-standard code in the same way. In fact, even the standardized code is not very well supported certain web browsers, notably Internet Explorer. The race to add more features at the expense of standards-compliance is known as the Browser Wars, and has led to a situation where very few websites display properly in all the major web browsers. From 2002 until late 2006 the Browser Wars have been very cool with little development done on IE, the most popular web browser in use today. However, in late October 2006 both IE and Firefox (IE's current arch-foe) released new versions of the software. This has renewed interest and awareness of the subject, especially in light of severe security flaws in the new IE7.

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When you open your browser, you want to see a good web site design staring back at you. The person who does the nice website design probably is a good website designer or hired a web site person who is a good web site designer for the site.

a Web Browser logo

The first web browser was written by Tim Berners-Lee, who also invented HTML, HTTP, and wrote the first web server. The WorldWideWeb web browser was intended for use by physicists working in labs in different parts of the world, thus the HTML language that it supported was designed to be very easy to learn (for physicists). The language is based upon hierarchical outline structure, with tags spread through out the text that define the presentation of the page in question. In the 15+ years since its invention, HTML has moved away from its original goal of defining the layout of webpages, to defining the meaning of its contents. Separate technologies, such as CSS, are responsible for defining page layout today.